Gut Microbiome

Ethyl caffeate alleviates NAFLD by modulating JNK/IRS-1/AKT signaling and the gut microbiota.

TL;DR

Ethyl caffeate ameliorates NAFLD potentially through dual direct (hepatic insulin signaling) and indirect (gut-liver axis) mechanisms, highlighting its potential as a promising natural candidate for NAFLD therapy.

Key Findings

Ethyl caffeate (EC) dose-dependently improved metabolic disturbances in high-fat diet (HFD)-fed mice, reducing body weight gain, liver index, and serum transaminases.

  • In vivo model used HFD-fed mice with EC administered at multiple doses
  • Endpoints included body weight gain, liver index, serum transaminases (ALT/AST), and hepatic triglyceride and cholesterol levels
  • EC treatment enhanced glucose tolerance and insulin sensitivity in HFD-fed mice
  • Effects were described as dose-dependent across EC treatment groups

EC alleviated insulin resistance and lipid accumulation in vitro in oleic acid (OA)-induced HepG2 cells in a dose-dependent manner.

  • In vitro model used oleic acid (OA)-induced HepG2 cells to mimic hepatic lipid accumulation
  • EC reduced hepatic triglyceride and cholesterol levels in HepG2 cells
  • Effects were consistent with the in vivo findings in HFD-fed mice
  • Dose-dependent improvements in metabolic parameters were observed

EC mechanistically alleviated insulin resistance by inhibiting aberrant phosphorylation of JNK and IRS-1, thereby restoring AKT activation.

  • EC inhibited aberrant phosphorylation of JNK (c-Jun N-terminal kinase) and IRS-1 (insulin receptor substrate-1)
  • Restoration of AKT activation was observed following EC treatment
  • This signaling axis links inflammation to insulin resistance in the hepatic context
  • Network pharmacology prediction was used to identify this mechanistic pathway prior to experimental validation

EC suppressed expression of the lipogenic transcription factor SREBP-1c and the inflammatory cytokine TNF-α.

  • SREBP-1c (sterol regulatory element-binding protein 1c) expression was reduced by EC treatment
  • TNF-α (tumor necrosis factor-alpha) expression was concurrently suppressed
  • These molecular changes correspond to reduced lipid synthesis and inflammation in NAFLD
  • Findings were identified through both in vivo and in vitro experimental models

EC remodeled the gut microbiota by decreasing the Firmicutes/Bacteroidota ratio and specifically enriching the beneficial genus Akkermansia.

  • Gut microbiota composition was assessed using 16S rRNA gene sequencing of cecal contents
  • EC treatment decreased the Firmicutes/Bacteroidota ratio, a marker commonly associated with metabolic health
  • Specific enrichment of Akkermansia, a genus associated with metabolic benefits, was observed
  • These microbiota changes suggest an indirect hepatoprotective mechanism via the gut-liver axis

EC modulated cecal metabolite profiles, particularly affecting bile acid, fatty acid, and amino acid metabolism pathways.

  • Untargeted metabolomics of cecal contents was used to characterize metabolite changes
  • Three major affected metabolic pathways were bile acid metabolism, fatty acid metabolism, and amino acid metabolism
  • Metabolomic changes complement the microbiota remodeling findings
  • These metabolic pathway alterations are consistent with known gut-liver axis interactions in NAFLD

Network pharmacology prediction was used to identify EC's potential targets and mechanisms in NAFLD prior to experimental validation.

  • Network pharmacology was employed as a predictive computational approach to guide mechanistic investigations
  • Predicted targets included components of the JNK/IRS-1/AKT signaling pathway
  • Network pharmacology findings were subsequently validated through in vivo and in vitro experiments
  • This integrative approach combined computational prediction with experimental verification

What This Means

This research suggests that ethyl caffeate (EC), a natural compound found in plants with known anti-inflammatory and antioxidant properties, may help treat non-alcoholic fatty liver disease (NAFLD) — the most common chronic liver disease worldwide, for which no specific drug treatment is currently approved. Using computer-based prediction, mouse models fed a high-fat diet, liver cell experiments, and analyses of gut bacteria and gut metabolites, the researchers found that EC reduced fat buildup in the liver, improved blood sugar regulation, and reduced insulin resistance in a dose-dependent way, meaning higher doses had stronger effects. The study identified two potential mechanisms by which EC might work. First, EC directly affected the liver by correcting a faulty molecular signaling chain (the JNK/IRS-1/AKT pathway) that normally drives insulin resistance and fat accumulation when dysregulated. It also reduced activity of a protein that promotes fat production (SREBP-1c) and lowered levels of an inflammatory molecule (TNF-α). Second, EC altered the gut microbiome — the community of bacteria living in the intestines — in beneficial ways, including increasing the abundance of a bacterium called Akkermansia that is associated with better metabolic health, and shifting the balance of bacterial communities in a direction typically associated with improved metabolism. These gut changes were accompanied by shifts in the types of metabolites (chemical byproducts) produced in the gut, particularly those involved in bile acid, fatty acid, and amino acid processing. This research suggests EC works through a 'dual mechanism' — directly improving liver function and indirectly doing so by reshaping the gut environment, which in turn influences the liver. These findings position EC as a potentially promising natural compound for future NAFLD therapy, though further research including human clinical studies would be needed to confirm these effects.

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Citation

Qi M, Qin F, Wang R, Zhang Y, Yue X. (2026). Ethyl caffeate alleviates NAFLD by modulating JNK/IRS-1/AKT signaling and the gut microbiota.. Food & function. https://doi.org/10.1039/d6fo03689a